Just tying a string to a tree would not be a valid eruv. One needs to have a "Tzruat Petach" which means that it needs to appear similar to a doorway with a "lechi" which is the doorpost and the "mashkof" which in this case would be the string.
So one needs to affix to the tree a post, such as a piece of wood. One would then attach the string directly above this post.
You can buy it in the dollar tree
ede
Magic string can be made from magic roots, obtained from a player-owned magic tree, by using a spade on it once its fully cut down.
you put it on a string and hang it on the tree
because it was used to hang on the Christmas tree as an ornament
for string players we call it "ROSIN" or the brick of tree sap that we put on our bows to make the produce sound when played on the strings.
A flexible tape measure is best. A string will do also. Just wrap the string around the tree until it doubles up on its self, then measure the string.
The Bark
yes, but you will need a large amount of string, four bananas and some turkey
You can make it into a belt, Christmas tree decor, present ribbon, and string.
leaves
There are many different crafts that can be done. You can string cranberries on a string to drape the tree. If you have kids than you can make the paper ring chains. You can also make cotton ball snowmen or perhaps visit the craft store and make your very own wreath.